1) Maybe try using the "Mets" as a border or Side of the cake.... Top/Focal point is based upon "family" and I would use Crucifix to represent Jesus within the center as a 3D element. Maybe add a stained glass effect on the cake board or outer top edge/border of cake (similar to a framed picture)

2) Use the Cross/Crucifix in the Center of cake... then let the four corners (Top Left, Top Right, Botton Left and Bottom Right) represent... family, sports, Jesus & put an inscription that ties them all together, somehow??

Is it meant to be a humorous cake? How complex do you want/need to make it? For an easy option you could photoshop some images together and then put them on a single edible icing sheet and/or border. Or what about a Mets scoreboard featuring Jesus and the family members? I see that the Mets have their own magazine. Why don't you photoshop this, personalising it with everything to do with the family and their faith... You can just use the outline frame of the magazine but then add the family's photos and little snippets about them, etc...I've done this kind of idea a few times (links below) on slab cakes and people love them!